How to tell if someone’s a programmer

“A woman asks her husband, a programmer, to go shopping:
– Dear, please, go to the nearby grocery store to buy some bread. If they have eggs, buy 6.
– O.K., hun.
Twenty minutes later the husband comes back bringing 6 loaves of bread. His wife is flabbergasted:
– Dear, why on earth did you buy 6 loaves of bread?
– They had eggs.”